| 摘要 |
To determine whether a bank note (2) is valid, either in a note sorter or in a separate unit, part of the note is illuminated with X-rays (10) and the resultant fluorescent X-rays (13) are detected and counted. A marker element such as barium in the form of barium sulphate is incorporated in place of part of the filler in intaglio ink used in bank notes. Different note denominations can have different combinations of markers to produce different fluorescent X-ray energies, which can be detected and analyzed to control sorting of the notes into the respective denominations at high speed. This arrangement also permits detection of worn notes and notes which are stuck together. An X-ray tube or radio-active source (8) has a fail safe shutter (11) and collimating shield (9). Alternatively the source may be annular with an intrinsic Germanium detector positioned on its axis. The presence of a note over the lead back-plate 6 is detected by photocells 7. <IMAGE> |
